FIG. 17 illustrates a layout of a general-type exhaust gas removal apparatus for a semiconductor manufacturing apparatus. In a semiconductor manufacturing apparatus 100, semiconductor substrates are processed using a variety of processing gases in a vacuum chamber 102, and the processing gas is discharged from the vacuum chamber 102 with a vacuum pump 104 and fed to an exhaust gas abatement device 106 connected to a downstream side (an outlet side) of the vacuum pump. The hazardous gas is then processed to become a non-hazardous gas that in turn is fed to an gas exhaust duct 108. As the exhaust gas contains an ingredient having a low vapor pressure at ambient temperature, it may become solidified at the time when the pressure downstream of the vacuum pump 104 elevates, and may then adhere to an exhaust pipe member and become deposited thereonto. For instance, such an ingredient may include but is not limited to aluminum chloride (AlCl3) discharged in an etching process for aluminum wiring, ammonium chloride (NH4Cl) derived in a process for forming a film of silicone nitride (SiN) or titan nitride (TiN), and tetraethyl silicate (TEOS) used in forming a film of silicone oxide (SiO2).
Further, the exhaust gas may contain an ingredient that may produce a solid product upon reaction with water. For instance, such an ingredient may include but be not limited to BCl3 to be used in etching for aluminum wiring, and SiCl4 to be discharged upon etching a polysilicon with a Cl-type gas. These solid products may be stuck to an exhaust pipe member close to an inlet of the exhaust gas abatement device and deposited thereon because humidity in the gas exhaust pipe member becomes high in the case where the exhaust gas abatement device is of a wet type using water for the removal of a hazardous ingredient.
The adherence and deposit of the solid products in the pipe member may be generally prevented, for example, by winding an exterior portion of the gas exhaust pipe member for flowing exhaust gas with a heater and heating the gas exhaust pipe member or other processes.
The gas exhaust pipe member, however, is provided, for example, with a variety of valves or branch pipe members and a bypass pipe member connecting an upstream side (an inlet side) to a downstream side (an outlet side) of the exhaust gas abatement device, and so on, and the pipe construction may be rendered complex at many points, and thus it becomes difficult to wind the heater around the pipe member as a whole in an appropriate fashion. Therefore, problems may result, for instance, that a solid product may adhere to and deposit inn a valve unlikely to be heated or that a solid product may adhere to a portion of the pipe member where flow of an exhaust gas may slow due to a complicated pipe construction. Moreover, in the case where the exhaust gas abatement device for processing exhaust gas into a non-hazardous gas is of a wet type where the exhaust gas is brought into contact with water, a humidity may become too high at a portion of the pipe member close to the inlet of the exhaust gas abatement device, whereby it may become impossible to heat the portion thereof to a sufficiently high degree. In particular, in the case where the exhaust gas contains an ingredient producing a solid product upon reaction with water, it may present the problem that the solid product formed due to such a high level of humidity is likely to adhere to and deposit on the portion of the pipe member.
In view of the foregoing problems, the present invention has been made with the object of providing a method and an apparatus for preventing adherence and deposit of a solid product in a gas exhaust pipe member for discharging exhaust gas.